The present invention relates to an apparatus for pulling rolling bearings from a retainer, as well as a use of such an apparatus and a method for such bearing pulling.
By definition rolling bearings include ball bearings as well as roller bearings. The invention is particularly well suited for pulling roller bearings in general and spherical radial roller bearings in particular.
Rolling bearings may in some cases by retained by press fit in a retainer therefor. For example, the retainer may be an end of a drying cylinder in a paper-making machine. After longtime use, perhaps decades, there may be a need to change the bearing because of irregular running and noise caused by wear. The bearing in question often has its outer ring very firmly stuck in the retainer. It is desirable to change the bearing without having to remove the bearing retainer from the shaft extending therethrough, especially in the case of bearings used within industry where machine stoppages have to be made as short as possible so as to keep the costs thereof low.
Pulling apparatuses for rolling bearings are already known by the CH patent publication 421 018 and the European patent application 0087895. These apparatuses have gripping means which grip the outer ring of the bearing and the inner ring as well as the outer ring of the bearing, respectively, so as to pull the bearing away from a retainer therefor (see especially said European patent application). However, these apparatuses may only be used to pull ball bearings, and the gripping means thereof do not grip the bearing in such a way that they can pull bearings which have their outer rings very firmly stuck in a retainer.
For example, spherical radial roller bearings are used for drying cylinders in paper-making machines. Those bearings are firmly retained in ends or gables fixed on both sides of the cylinder in base plates. The known apparatuses mentioned above cannot pull such bearings from the retainer (the gables) with the shaft projecting through the gable and the bearing, at least where no acceptable grip may be obtained in any of the races of the bearing of this type. The conventional procedure used for changing such bearings has consisted of first removing the gable in question from the base plate and removing the gable from the cylinder by pulling it over the shaft end thereof and then pressing or striking the bearing out of the gable with a suitable tool. A new bearing is then pressed into the gable which is moved over the shaft and secured to the base plate again. This procedure is very time-consuming- It may lead to dismantling of the driving arrangement for the shaft- It also generates high maintenance cost and, probably more importantly, high direct labor costs because of the machine downtime.